API reference · CAIN Trajectory

Evaluate Counterfactual

POST /fabric/trajectories/{trajectory_id}/counterfactual

Last reviewed 2026-11-06

POST /fabric/trajectories/{trajectory_id}/counterfactual

Run counterfactual trust simulation on a trajectory: - Omission: What would trust score be if step K never occurred? - Minimum evidence: What is required to permit a blocked action?

Parameters

Name	In	Type	Meaning
`trajectory_id` required	path	string

Request body

CounterfactualRequest (required)

Field	Type	Meaning
`omitted_step`	integer or null
`proposed_action`	string or null
`proposed_resource`	string or null
`proposed_risk`	number or null	default `0.1`

Responses

Status	Meaning	Body
`200`	Successful Response	object
`401`	The X-API-Key header is missing, or the key is unknown, revoked or replaced.	`Error`
`403`	The key is valid but may not do this (for example an agent key approving its own held action).	`Error`
`422`	Validation Error	`HTTPValidationError`
`429`	Rate limit or monthly quota reached. Wait for the number of seconds in Retry-After when it is sent.	`Error`

Try it

Your API key X-API-Key Remember the key in this tab onlytrajectory_id pathRequest body application/json

This call changes data in the account the key belongs to.

The request goes from your browser straight to this site. Your key is not stored unless you tick the box, and then only in this tab's session storage.

Code

curl -sS -X POST 'https://cainstudio.online/fabric/trajectories/<trajectory_id>/counterfactual' \
  -H "X-API-Key: $CAIN_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"proposed_risk": 0.1}'

import json, os, urllib.request

req = urllib.request.Request('https://cainstudio.online/fabric/trajectories/<trajectory_id>/counterfactual', method='POST',
    headers={"X-API-Key": os.environ["CAIN_API_KEY"], "Content-Type": "application/json"},
    data=json.dumps({
      "proposed_risk": 0.1
    }).encode())
with urllib.request.urlopen(req, timeout=60) as r:
    print(r.status, json.load(r))

const res = await fetch("https://cainstudio.online/fabric/trajectories/<trajectory_id>/counterfactual", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.CAIN_API_KEY!,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "proposed_risk": 0.1
  }),
});
console.log(res.status, await res.json());

Schemas used

Error · HTTPValidationError · ValidationError · CounterfactualRequest

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